NavigationBar的使用及创建

说明. 创建一个navigationBar 一个bar中有一个item，每个item中可以有许多个UIBarButtonItem

1. 创建一个bar

UINavigationBar *bar = [[UINavigationBar alloc] initWithFrame:(CGRect){0,20,width,46}];
        UIImage *backImage = [UIImage imageNamed:@"statuBarBackground"];
        backImage = [backImage imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
        [bar setBackgroundImage:backImage forBarMetrics:UIBarMetricsCompactPrompt]; // 背景透明
        
        NSMutableDictionary *dict = [[NSMutableDictionary alloc] init]; // title字体属性
        [dict setValue:[UIColor colorWithRed:190/255.0 green:32/255.0 blue:0/255.0 alpha:1] forKey:NSForegroundColorAttributeName];
        [dict setValue:[UIFont systemFontOfSize:18] forKey:NSFontAttributeName];
        
        [bar setTitleTextAttributes:dict];

2. 创建一个item

UINavigationItem *item = [[UINavigationItem alloc] init];

3. 创建一个barbuttonItem

UIBarButtonItem *back = [[UIBarButtonItem alloc] initWithImage:image style:UIBarButtonItemStylePlain target:self action:@selector(backToOriginal:)];

或自定义：

UIButton *leftBtn = [[UIButton alloc] initWithFrame:(CGRect){0,0,32,32}];
        [leftBtn setBackgroundImage:image forState:UIControlStateNormal];
        leftBtn.contentMode = UIViewContentModeCenter & UIViewContentModeScaleAspectFit;
        [leftBtn addTarget:self action:@selector(backToOriginal:) forControlEvents:UIControlEventTouchUpInside];
        
        UIBarButtonItem *back = [[UIBarButtonItem alloc] initWithCustomView:leftBtn];

4. 将，buttonitem添加到item上

item.leftBarButtonItem = back;

5. 将item添加到bar上

[bar pushNavigationItem:item animated:NO];